1. Field of the Invention
The present invention relates to an apparatus and method for testing the picture quality of a liquid crystal display, and in particular, to a picture quality testing apparatus and method of a liquid crystal display which can measure at least any one of gray inversion and color shift.
2. Description of the Related Art
A liquid crystal display (LCD) displays images by controlling the light transmittance of a liquid crystal by an electric field. To this end, the LCD includes an LCD panel in which liquid crystal cells are arranged in the form of matrixes, and a driving circuit for driving the LCD panel.
The LCD panel includes a thin film transistor substrate and a color filter substrate which face each other, a liquid crystal injected between the two substrates, and a spacer for maintaining a cell gap between the two substrates.
The thin film transistor substrate has gate lines, data lines, thin film transistors formed with switching elements at the intersection of the gate lines and the data lines, pixel electrodes connected to the thin film transistors in the unit of liquid crystal cells, and an alignment film coated on those whole elements. The gate lines and data lines receive signals from the driving circuit through their respective pads. The thin film transistors provide the pixel electrodes with pixel signals supplied to the data lines in response to scan signals supplied to the gate lines.
The color filter substrate includes color filters formed in the unit of liquid crystal cells, a black matrix for separating the color filters from one another and reflecting external light, a common electrode for supplying a reference voltage to the liquid crystal cells, and an alignment film coated on those whole elements.
In a conventional LCD, there frequently occur gray inversion that a gray level is inverted and color shift that color is changed when its screen moves in up/down directions or in right/left directions. However, since there are no definite ways of testing the gray inversion and color shift, those phenomena are felt and evaluated through the human eyes. Therefore, an apparatus which is capable of measuring the gray inversion and color shift has been in demand.